If you are a municipal health manager, you have probably already heard of the RNDS and HL7 FHIR - especially after the publication of Ordinance 3,232/2024 and Technical Note 12/2025. But what do these terms mean in practice? Why do they matter for your municipality? And what do you need to check in the system you use today?
This article answers these questions directly - both for managers who need the strategic overview and for technical teams who need the implementation details.
What the RNDS is
The RNDS (National Health Data Network) is the digital infrastructure created by the Ministry of Health to connect every point of the Brazilian health system in a single network for exchanging clinical information.
The goal is ambitious: that any health professional, anywhere in the country, can access a patient's relevant clinical history - regardless of where they were previously treated. A triage nurse at an emergency care unit (UPA) in São Paulo can retrieve the medication history of a patient seen at a UBS (basic health unit) in the interior of Paraíba. A hospital emergency room can access the results of exams done in primary care weeks earlier.
For this to work, systems from different vendors, in different municipalities and states, need to speak the same language. That is where HL7 FHIR comes in.
What HL7 FHIR R4 is
HL7 (Health Level Seven) is an international organization that defines standards for exchanging health information. FHIR (Fast Healthcare Interoperability Resources) is that organization's most modern standard - a technical specification that defines how clinical data should be structured and transmitted between health systems.
Version R4 (Release 4) is the version adopted by the Ministry of Health as the mandatory standard for integration with the RNDS.
In practical terms, HL7 FHIR R4 defines:
- Resources: standardized units of data (Patient, Encounter, Medication, Lab Result, etc.)
- REST API: how systems communicate to send and receive these data
- Profiles: adaptations of the international standard to the Brazilian reality, defined by the Ministry of Health
Why FHIR is better than previous standards
Before FHIR, the dominant standard for exchanging health data was HL7 v2 - a specification created in the 1980s that, although widely adopted, is hard to implement, inflexible and ill-suited to the world of modern web APIs.
FHIR brought three fundamental advances:
1. REST architecture: systems communicate over HTTP, the same protocol as the web. This drastically simplifies integration compared with HL7 v2's proprietary protocols.
2. Data in JSON or XML: formats widely supported by all modern programming languages.
3. Extensibility: the standard defines a mandatory minimum core and allows extensions for specific needs - such as the Brazilian extensions defined by the Ministry of Health for the RNDS.
What the RNDS requires in practice
Integration with the RNDS involves two main flows:
Sending data (Sender)
The municipal system sends clinical records to the RNDS in the formats defined by the Ministry. The mandatory documents for APS (primary health care) include:
- Discharge Summary: summary of hospital care
- Laboratory Test Result: results of tests performed in the municipal network
- Clinical Encounter Record: records of primary care visits (being implemented progressively)
- Medication Dispensing: dispensing records from pharmacies in the municipal network
Querying data (Receiver)
The municipal system can query the RNDS to access a patient's clinical data recorded by other points in the national network - care history, previous exams, medications in use.
What managers need to check
For managers without a technical background, the right questions to ask the system vendor are:
1. Is the system certified to send data to the RNDS via HL7 FHIR R4?
Require proof - a certification document or official technical documentation.
2. Which FHIR resources does the system support?
Check whether the mandatory documents for APS are implemented.
3. Does the system comply with the Brazilian profiles defined by the Ministry of Health?
FHIR allows national adaptations. The Brazilian profiles define specific rules - such as additional mandatory fields - that the system must respect.
4. What is the authentication mechanism with the RNDS?
Communication with the RNDS requires an ICP-Brasil digital certificate. The vendor should explain how this process is managed.
5. How does the system handle sending errors?
Records rejected by the RNDS must be identified and resubmitted. The system should have an error management mechanism.
What technical teams need to know
For municipal developers and IT analysts, a few relevant technical points:
Authentication
The RNDS uses OAuth 2.0 with an ICP-Brasil digital certificate for authentication. The certificate is issued in the name of the health facility (CNES) and must be renewed periodically.
Endpoints
The RNDS has a certification environment (for testing) and a production environment. The correct cycle is: development → testing in the certification environment → certification → production.
Resource validation
The Ministry of Health provides an official FHIR resource validator for the Brazilian context. All resources must be validated against the national profiles before being sent to production.
Monitoring
Data submission to the RNDS must be monitored continuously. Communication failures or silent rejections can result in gaps in national records - and affect federal funding tied to data quality.
DHF's integration with the RNDS
The DHF platform natively implements HL7 FHIR R4 support for integration with the RNDS, following the Brazilian profiles defined by the Ministry of Health. The technical architecture includes:
- BTS module (Service Exchange Bus) for communication with the RNDS
- RAS Runners module for recording clinical encounters
- Collection and integration of structured clinical data
- Electronic health record with export in FHIR format
The entire architecture is developed in strict compliance with the LGPD (Brazil's General Data Protection Law) and the ISO 27001 information security requirements.
Have questions about how to ensure your municipal system's integration with the RNDS? Talk to our technical team - we work directly with municipal IT teams.
